Surgery for anismus

Anismus or the non-relaxing puborectalis muscle on straining affects 44% of constipated patient suffering from obstructed defecation [1] and can be considered a cause of constipation [2] and a marker of multisite functional disorders [3].

This means that patients with anismus may present with different symptoms, including anxiety and depression, which have to be taken into accountas they may render their chance of cure rather difficult.

Conservative measures, such as pelvic floor rehabilitation biofeed-back [4] and Botulinum toxin injection [5], have been used to manage this condition.

Anismus is seen “through surgical eyes” [6], and several authors have considered miotomy to be an effective method to effectively relax a tense puborectalis muscle, which can be the cause of obstructed defecation.

Initially, experienced surgeons [7] suggested caution, reporting that “a variety of surgical measures have failed.” However, recently, it has become clear that “management of anismus involves colorectal surgeons” [8].

Division of the puborectalis muscle, which does not relax on straining in patients with anismus, is the crucial maneuvre aimed at releasing the tension and allowing effective defecation.

At the end of last century, surgeons at St Mark’s Hospital in London, where I had the opportunity to see this procedure carried out by Peter Hawley, completely divided the posterior part of the muscle. However, the operation was abandoned because it frequently led to anal incontinence.

The more conservative treatment, bilateral partial miotomy, provided better functional results, although a systematic review and meta-analysis by the Wexner group [9] reported disordered continence in 12% of case. Notably, some of the reviewed patients had a complete muscle division and others an internal sphincterotomy. The anismus cure rate was 70% at 1 year, similar to the findings of Asciore et al. (75%).

None of the patients who had a partial bilateral miotomy performed by Farid et al. (2010) and by us suffered from permanent anal incontinence at 1 year. The Egyptian authors reported that in 95% of patients, anismus was cured, compared with 70% after Botulinum toxin injection.

Recently [10], the author of this article reported a modified bilateral partial miotomy of the puborectalis, using a minimally invasive approach. None of the operated patients experienced bleeding, sepsis, or rectal injury, and no cases of anal incontinence were observed.

As cases of postoperative anal incontinence were reported in the review carried out by Emile et al. in those patients who had an anal internal sphincterotomy associated with the puborectalis miotomy, one wonders whether it is functionally safe to divide the internal sphincter in case of anal hypertone associated with anismus. According to a large series published by Abdelnaby et al. in 2021 [11], the answer is yes. None of the patients operated on experienced permanent anal incontinence. Both anismus and anal spasm were cured in 89% of 73 patients at 1 year. Notably, most patents were male, whereas most patients suffering from obstructed defecation and anismus were women.

When treating female patients, expecially if multiparous, the physician should be more conservative. A course of bio-feedback [12] before carry out surgery, aimed at avoiding a potentially dangerous operation, is mandatory.

Looking at our first series, it should be noted that the only patient with occasional incontinence after the bilateral partial miotomy was a female who had had one vaginal delivery.

However, the only recurrence of anismus following the novel minimally invasive procedure was a young man suffering from both anxiety and depression. Let me remind readers of Bouchucha and Devroede's definition: anismus is a marker of multisite functional disease.

The first site is the brain, as in our patient. Unfortunately he refused treatment by a psychiatrist or psychologist. It is wise not to operate on such patients.

For optimal preoperative selection, the “draw-the-family test,” a graphic reactive test aimed at investigating the patient's psychological pattern, can be used. It can be quickly performed and evaluated by the surgeon in the office [13].

In conclusion, there are three considerations:

1. the procedure, i.e. bilateral partial division of the puborectalis for anismus, can be considered safe, as postoperative morbidity is very low, and no case of permanent anal incontinence has been reported in the literature

2. however, the operation is not necessarily effective, as the series reported in the literature consist of < 300 patients in 2 decades, and no authors have reported a sufficiently long follow-up period, i.e. > 1 year.

3. careful patient selection is mandatory, aiming to avoid operating on those with weak sphincters or with mental illness.

Funding

The manuscript did not receive any type of funding.

Declarations

Conflict of interest

The author discloses no conflict of interest.

Ethical approval

This article is an editorial and does not contain any new primary research involving human participants or animals performed by the author. Therefore, ethical approval was not required.

Informed consent

For this type of study, formal informed consent is not required as no new individual patient data is being reported.